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PS Audio Stellar M1200 Amplifier

PS Audio Stellar M1200 Amplifier

Mention the words “switching” and “amplifier” in tandem and not a few audiophiles are apt to get a queasy look. The knock on Class D amplification is that it tends to sound cold, sterile, amusical. For the most part, there has been something to the opprobrium that has attached to switching amplifiers. So when I saw that PS Audio’s inventive engineer Darren Myers had come up with a switching amplifier called Stellar M1200, I was most curious to hear it. 

The design of the monoblock M1200, which is priced at $5998 per pair, seems calculated to try to overcome the traditional objections to Class D amplifiers. The input section features a venerable 12AU7 tube coupled to a high-current ICE Edge output section. The idea, as near as I can tell, is to try and mate beauty and the beast. And why not? The advantage of Class D amplifiers is that they don’t really produce any significant heat, weigh very little, consume minimal electricity, and deliver a whopping amount of power—in the case of the M1200 no less than 1200 watts into a 4-ohm load, enough to drive just about any extant loudspeaker with ample headroom to hit sonic peaks loud enough to satisfy the most demanding listener.

When I first spotted the M1200, I reckoned that it would be able to drive my Wilson WAMM Master Chronosonic subwoofers easily. I couldn’t help wondering what all that power would be like on the bottom section of my loudspeaker setup. As it happened, however, my system was in flux, with gear whizzing in and out the door; so, I put the M1200s first on the WAMM main loudspeakers without harboring too great expectations. Boy, was I in for a surprise! The M1200 is not a good amplifier; it is a superb one.

There were several enticing attributes of the M1200 that caught my ear, so to speak, from the get-go. The first one was the capacious soundstage that the M1200 produces. It’s always been my experience that the more powerful the amplifier, the larger and deeper the soundstage created by the loudspeaker. Joined to this is a sense of hall ambience, which is very important for a classical buff like me. The M1200 produced all of these in spades. 

On a fine Delos CD of the Brazilian Guitar Quartet playing transcriptions of Bach’s four suites for orchestra, the plusses of the M1200 were easy to detect. For one thing, there was a whoosh of air the instant the quartet began playing the second suite, each guitar firmly and forcefully planted in its own space. One of the attributes of the power that the M1200 offers is a sense of power and drive, not just of the overall performance but of a feeling of dynamic jump for each instrument. To a greater degree than I have heard with most amplifiers, the M1200 truly amplifies the smallest details—the hand of a guitarist inadvertently brushing the strings, a performer sucking his breath in, and so on. The accumulation of these small, almost microscopic, details add up to a more realistic overall sonic landscape. Instruments, whether trumpet, guitar, or violin, emerge as formidable in size and scale.

At the same time, the M1200 is something of a jackrabbit. The amazing damping factor of the amplifier means that it often seems to start and stop a hair faster than many other of its brethren. No matter the musical genre, the feeling of a sense of propulsion is inescapable. In many ways, the music seems to be happening in real time as opposed to that subliminal sense of a split-second time lag. On a Philips LP of Schubert’s sonatas for violin and piano that’s beautifully played by Arthur Grumiaux and Paul Crossley, this alacrity endows the music with a sense of drama. Grumiaux’s bowing has more bite and fervor than most systems would render, as do Crossley’s fortissimos. In my experience, it’s pretty difficult to reproduce a violin’s overtones—the guts of the sound—with any real degree of verisimilitude. The M1200 excels at it. The hall ambience it coaxes into your listening room also means that the lower regions of the piano resound with great fidelity. The piano chords have a 3-D dimensionality to them that is quite winning, particularly in the bass region. Ah, the bass region. I’ll admit it. I’m something of a bass fanatic, and not just because my system is located in the basement. Nor is it that I’m intent on pounding out the low bass on rock recordings, though I’ll confess that I enjoy it upon occasion. No, what I really find illuminating is the degree to which improvements in the bass further the illusion of the real thing throughout the frequency spectrum. In controlling the bass quite authoritatively, the M1200 is able to reproduce effectively the timbral richness of a grand piano, tuba, or guitar. It goes deeper than many competing amplifiers, something that came through vividly on a Pentatone SACD of Bram Beekman playing Bach’s Organ Concerto in D minor. The sustained low organ notes are held with a tautness, even as the melody plays above, that makes for a rewarding listening experience. Ditto for a praeludium by Johann Christoph Kellner; I’ve never heard it better. The linearity of the amplifier means that every note, from bass to treble, exploded out of the loudspeaker with equal force on massive organ block chords. The sound was rich and overwhelming. The depth of hall space was cavernous, as though you were in the cathedral itself feeling the sonic waves emanating from the organ. Forget about the fumbling around that you sometimes hear with other amplifiers that are trying to grasp the very lowest reaches of the organ. The M1200 handles them with aplomb. You’ll hear every note, loud and clear. 

What about the treble region? Here, as you might expect, there are some plusses and minuses. The excellent transparency and power of the M1200 allow it to soar wide open in this fussy sonic region. The grip and control on violin and piano or vocals is most impressive. Take the German counter-tenor Andreas Scholl. On a Harmonia Mundi recording of Bach cantatas, it is impossible to detect a hint of compression with the M1200 when Scholl cuts loose. You can also practically hear the air whooshing through the organ pipes on contemplative treble passages. The automotive equivalent would be flooring it on the Autobahn with no sense of hesitation. The power with the M1200, in other words, is always there, always on tap, always ready to deliver. 

But—you knew there was a “but” coming—the M1200 is simply not on the level of costlier amplifiers in offering an unimpeachable treble region when it comes to tonality. In my view, the M1200 closes the gap between switching and Class A/B amplifiers to a remarkable degree—but not all the way. It has great clarity, but simply remains a little tonally thinner on top than other top-flight amplifiers.

The M1200 poses a real challenge for much of the audio industry. It offers a colossal sound and excellent refinement at what has to be considered a budget price for the high end. PS Audio, which has specialized in power regeneration for many years, is really expanding its ambit. For anyone who has a loudspeaker that is difficult to drive the M1200 is a must-audition. It does so many things so well that it is consistently a joy to listen to in my system. 

Of the amplifiers that I’ve auditioned in this price range, the Stellar M1200 is by far the best, a gangbuster piece of gear that upends many old verities about switching amplification. I could live with it for a very long time. Stellar, indeed.

Specs & Pricing

Frequency response:10Hz–20kHz ±0.5dB, 10Hz–45kHz +0.1dB, -3.0dB
Output power: 600W into 8 ohms, 1200W into 4 ohms.
Signal to noise: > 112dB, 1kHz@1200 watts
Gain: 30.5dB
Output impedance: <0.007 ohms, 50Hz, 2.8Vrms
Damping factor: >550 at 50Hz, 2.8Vrms, 4 ohms; >1100, 8 ohms
Inputs: RCA (unbalanced), XLR (balanced)
Outputs: Copper-base nickel-plated binding posts (two pair)
Dimensions: 17″ x 3.75″ x 12″
Weight: 27 lbs. (each)
Price: $5998/pr.

Tags: POWER AMPLIFIER PS AUDIO

Jacob Heilbrunn

By Jacob Heilbrunn

The trumpet has influenced my approach to high-end audio. Like not a few audiophiles, I want it all—coherence, definition, transparency, dynamics, and fine detail.

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